TIG Torch Gas Fittings: 5/8-18 vs 9mm Quick Connect
By MIG/TIG/Stick Welders & Plasma Cutters | USA Weld – HTP ... | Published: 2026-10-29
Category: Comparisons
Learn the key differences between 5/8-18 threaded and 9mm quick-connect gas fittings for TIG torches, including compatibility and when to choose each.
Quick Answer
Choose a 5/8-18 threaded gas fitting for universal compatibility with most regulators and hoses; choose a 9mm quick connect for faster torch changes if your system supports it.
Why the fitting type matters
The gas fitting on your TIG torch determines how you connect it to your regulator or hose. Getting this wrong can lead to gas leaks, poor shielding, and wasted time. Understanding the two common types helps you buy the right torch the first time.
5/8-18 is a standard threaded connection widely used on TIG torches and regulators. It's reliable and easy to source. The 9mm quick connect is a push-to-connect style that allows faster torch changes, but it requires a matching receiver on your machine or hose.
Compatibility and trade-offs
If you already own a regulator or hose with a 5/8-18 fitting, a threaded torch is the simplest choice. Quick connect fittings are more convenient but less universal—you need the matching coupler on your setup.
For most hobbyists and professionals, the 5/8-18 is the safer default. Quick connect shines in production environments where you switch torches frequently.
Common Questions
- What is the difference between 5/8-18 and 9mm quick connect?
- 5/8-18 is a threaded connection that screws onto a regulator or hose. 9mm quick connect is a push-to-connect fitting that locks in place with a collar. Threaded is more universal; quick connect is faster to change.
- Which gas fitting should I choose?
- Choose 5/8-18 if you want maximum compatibility with standard regulators and hoses. Choose 9mm quick connect only if your existing setup already uses that type. Check your current regulator or hose before buying.
- Can I convert between 5/8-18 and 9mm quick connect?
- Yes, adapters are available, but they add another connection point that can leak. It's cleaner to match the fitting type from the start. If you use an adapter, tighten it carefully and check for leaks.
Torch with 9mm Quick Connect
- 17 Series (150A) Air-Cooled Torch w/35 Dinse & 9mm Quick Connect Gas Fitting: This air-cooled TIG torch includes a 9mm quick connect/disconnect gas fitting and a 35 Dinse power connection. If your welder or hose uses a 9mm quick connect, this torch lets you swap torches in seconds without tools.
17 Series (150A) Air-Cooled Torch w/35 Dinse & 9mm Quick Connect Gas Fitting
